Luminescent wheel, light source unit having luminescent wheel device including same luminescent wheel, and projector

ABSTRACT

A luminescent wheel includes a reflecting plate on which a diffuse plate and a luminescent material layer are provided in an end-to-end relationship with each other in a circumferential direction, a first supporting plate which is provided on one surface of the reflecting plate to support part of the diffuse plate, and a second supporting plate which is provided on the other surface of the reflecting plate to support part of the diffuse plate.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a Continuation application of U.S. Ser. No.14/841,591 filed on Aug. 31, 2015, which is based upon and claims thebenefit of priority under 35 USC 119 from the prior Japanese PatentApplication No. 2014-182295 filed on Sep. 8, 2014, the entire disclosureof both of which, including the description, claims, drawings andabstract, is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a luminescent wheel, a light sourceunit having a luminescent wheel device including the luminescent wheel,and a projector including this light source unit.

Description of the Related Art

In these days, data projectors are used on many occasions as an imageprojection system which projects an image of a screen or a video imageof a personal computer, as well as images based on image data which isstored on a memory card or the like on to a screen. In these dataprojectors, light emitted from a light source is caused to converge to amicromirror display device called a DMD (Digital Micromirror Device) ora liquid crystal panel so that a full-color image is displayed onto ascreen.

In addition, the application of such projectors is expanding widely fromcommercial presentation to domestic use as video equipment includingpersonal computers, DVD players and the like has been used generally.Conventionally, the mainstream of these projectors has been those whichutilize a high-intensity discharge lamp as a light source. In recentyears, however, there have been made various developments of projectorswhich use, as a light source, a plurality of semiconductor lightemitting elements such as laser diodes and which include a luminescentwheel which uses the semiconductor light emitting elements as excitationlight sources.

A projector disclosed in the Japanese Unexamined Patent Publication No.2012-37681 includes a red light source device and a luminescent wheeldevice. The luminescent wheel device has a luminescent wheel having aluminescent material layer on to which light in the blue wavelengthrange which is emitted from an excitation light shining device is shoneas excitation light to thereby emit luminescent light in the greenwavelength rage and a diffuse transmission area which diffuses andtransmits light emitted from the excitation light shining device. Theexcitation light shining device also functions as a blue light sourcesince light emitted therefrom is diffused and transmitted through thediffuse transmission area of the luminescent wheel.

In the luminescent wheel of the luminescent wheel device which isdisclosed in the Japanese Unexamined Patent Publication No. 2012-37681,an arc-shaped cut-out portion is cut in a disc-shaped metallic base, anda diffuse plate is provided in this cut-out portion. This luminescentwheel has the luminescent material layer which is provided in anend-to-end relationship with the diffuse plate in a circumferentialdirection, and the luminescent material layer is provided in an annularrecess portion provided on the mirror finished base. Because of this, itis difficult to machine the metallic base to provide the annular recessportion, and a certain length of machining time is required. Further,the metallic base needs to have a predetermined thickness for formingthe annular recess portion. This makes it difficult to form the cut-outportion through punching by using a press, and therefore, the cut-outportion is required to be formed through cutting. It is considered thatforming the cut-out portion through cutting takes a certain length oftime.

In recent years, a luminescent wheel 501 shown in FIG. 9 is used as aluminescent wheel in which the aforesaid problem with machining themetallic base is improved. In this luminescent wheel 501, a C-shapedpartially annular luminescent material layer 502 is provided on a frontside of a reflecting plate 510. A first diffuse plate supporting plate530 is provided on a back side of the reflecting plate 510 so as tosupport a diffuse plate 520. The diffuse plate 520 is fastened by clawportions 533 which are provided at both ends of a cut-out portion in thefirst diffuse plate supporting plate 530 so as not to come off in adirection in which a centrifugal force is applied when the luminescentwheel 501 rotates.

Further, a second diffuse plate supporting plate 540 is provided on aback side of the first diffuse plate supporting plate 530. Additionally,a front side of the diffuse plate 520 near an inner circumferential edge522 thereof is superposed on a back surface of the reflecting plate 510near an inner circumferential edge 512 of a cut-out portion in thereflecting plate 510. On the other hand, a back side of the diffuseplate 520 near the inner circumferential edge 522 thereof is superposedon a front side of an inner circumferential edge 542 of a cut-outportion in the second diffuse plate supporting plate 540. In this way,the diffuse plate 520 is held by the reflecting plate 510 and the seconddiffuse plate supporting plate 540 to be fixed to the luminescent wheel501.

Since the reflecting plate 510, the first diffuse plate supporting plate530 and the second diffuse plate supporting plate 540 of the luminescentwheel 501 shown in FIG. 9 are each formed of a thin metallic plate, thecut-out portions and the like can be machined through punching. Further,since the luminescent wheel 501 is formed by combining these disc-shapedthin plate materials together, the fabricating work becomes easy.

However, the luminescent wheel 501 shown in FIG. 9 is configured as thefour-layer construction of the first diffuse plate supporting plate 530,the second diffuse plate supporting plate 540, the reflecting plate 510and the luminescent layer 502, and therefore, the thickness of theluminescent wheel 501 is increased, thereby calling for an enlargementin size of the luminescent wheel 501. Although it is considered toreduce the respective thicknesses of those constituent members, it isrequired that the reflecting plate 501 has a predetermined thickness soas to be prevented from being thermally deformed when the reflectingplate 501 is mirror finished. Additionally, since the first diffuseplate supporting plate 530 fastens the diffuse plate 520 with the clawportions 533 in relation to the direction in which the centrifugal forceis applied, the predetermined thickness is required.

SUMMARY OF THE INVENTION

Thus, the invention has been made in view of these situations, and anobject thereof is to provide a luminescent wheel whose thickness isreduced, a light source unit which can be reduced in size by includingthe luminescent wheel, and a projector including the light source unit.

According to an aspect of the invention, there is provided a luminescentwheel including:

a reflecting plate on which a diffuse plate and a luminescent materiallayer are provided in an end-to-end relationship with each other in acircumferential direction;

a first supporting plate which is provided on one surface of thereflecting plate to support part of the diffuse plate; and

a second supporting plate which is provided on the other surface of thereflecting plate to support part of the diffuse plate; wherein

the luminescent material layer is formed on the reflecting plate.

According to another aspect of the invention, there is provided a lightsource unit including:

a luminescent wheel device including the luminescent wheel according tothe invention;

an excitation light shining device which is made up of a semiconductorlight emitting element to emit light in the blue wavelength range asexcitation light; and

a red light source device which is made up of a semiconductor lightemitting device to emit light in the red wavelength range, wherein

the luminescent material layer emits light in the green wavelength rangeas a result of the excitation light being shone on thereto.

According to a further aspect of the invention, there is provided aprojector including:

the light source unit according to the aforesaid aspect of theinvention;

a display device on to which light source from the light source unit isshone to form image light;

a projection side optical system which projects the image light emittedfrom the display device on to a screen; and

a projector control unit configured to control the display device andthe light source unit.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS

FIG. 1 is an external perspective view showing a projector according toan embodiment of the invention.

FIG. 2 is a functional block diagram of the projector according to theembodiment of the invention.

FIG. 3 is a schematic plan view showing an internal construction of theprojector according to the embodiment of the invention.

FIG. 4 is a front view of a luminescent wheel according to theembodiment of the invention.

FIG. 5 is an exploded perspective view of the luminescent wheelaccording to the embodiment of the invention.

FIG. 6 is a sectional view of the luminescent wheel according to theembodiment of the invention taken along a line VI-VI in FIG. 4.

FIG. 7 is a sectional view of the luminescent wheel according to theembodiment of the invention taken along a line VII-VII in FIG. 4.

FIG. 8 is a sectional view of the luminescent wheel according to theembodiment of the invention taken along a line VIII-VIII in FIG. 4.

FIG. 9 is a partial sectional view showing a conventional luminescentwheel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a best mode for carrying out the invention will bedescribed through the use of the accompanying drawings. It should benoted, however, that although the following embodiment includes variouslimitations which are technically preferable to carry out the invention,the scope of the invention will not be limited to the followingembodiment and illustrated examples.

Hereinafter, an embodiment of the invention will be described throughthe use of the accompanying drawings. FIG. 1 is an external perspectiveview of a projector 10. In this embodiment, when left and right arereferred to in relation to the projector 10, they denote, respectively,left and right with respect to a projecting direction, and when frontand rear are referred to in relation to the projector 10, they denote,respectively, front and rear with respect to a direction towards ascreen from the projector 10 and a traveling direction of a pencil oflight emitted from the projector 10.

As shown in FIG. 1, the projector 10 has a substantially rectangularparallelepiped shape. The projector 10 has a projection port to a sideof a front panel 12 that is a front side panel of a casing of theprojector 10, and this projection port is covered by a lens cover 19. Aplurality of inside air outlet ports 17 are provided in the front panel12. Further, although not shown, the projector 10 has an Ir receptionunit which receives a control signal from a remote controller.

In addition, a keys/indicators unit 37 is provided on an upper panel 11of the casing. Disposed on this keys/indicators unit 37 are keys andindicators which include a power indicator, a projection switch key, anoverheat indicator, and the like. The power indicator informs whether apower switch key or a power supply is on or off. The projection switchkey switches on and off the projection by the projector 10. The overheatindicator informs of an overheat condition occurring in a light sourceunit, a display device, a control unit or the like when they reallyoverheat.

Further, an input/output connector unit where USB terminals, an imagesignal input D-SUB terminal where analog RGB image signals are inputted,an S terminal, an RCA terminal, a voice output terminal and the like areprovided and (a group of) various types of terminals 20 including apower supply adaptor plug are provided on a back panel 13 at the rear ofthe casing. Additionally, a plurality of outside air inlet ports areformed in the back panel 13. Additionally, a plurality of inside airoutlet ports 17 are formed in each of a right side panel, not shown,which is a side panel of the casing, a left side panel 15 which is aside panel shown in FIG. 1 and the front panel 12. Outside air inletports 18 are also formed in a corner portion between the left side panel15 and the back panel 13.

Next, a projector control unit of the projector 10 will be described bythe use of a functional block diagram shown in FIG. 2. The projectorcontrol unit includes a control module 38, an input/output interface 22,an image transforming module 23, a display encoder 24, a display driver26 and the like.

This control module 38 governs the control of operations of circuitrieswithin the projector 10 and is made up of a CPU, a ROM which stores in afixed fashion operation programs of various types of settings, a RAMwhich is used as a working memory, and the like.

Image signals of various standards which are inputted from theinput/output connector unit 21 are sent via the input/output interface22 and a system bus (SB) to the image transforming module 23 where theimage signals are transformed so as to be unified into an image signalof a predetermined format which is suitable for display by the projectorcontrol unit. Thereafter, the image signals so transformed are outputtedto the display encoder 24.

The display encoder 24 deploys the image signals that have been inputtedthereinto on a video RAM 25 for storage therein and generates a videosignal from the contents stored in the video RAM 25, outputting thevideo signal so generated to the display driver 26.

The display driver 26 functions as a display device control module anddrives a display device 51, which is a spatial optical modulator (SOM),at an appropriate frame rate in response to the output of the imagesignal from the display encoder 24. In this projector 10, a pencil oflight that is emitted from a light source unit 60 is shone on to thedisplay device 51 via a light source side optical system, which will bedescribed later, whereby an optical image is formed by using reflectedlight reflected by the display device 51. The image so formed is thenprojected on to a screen, not shown, for display thereon via aprojection side optical system. A movable lens group 235 of theprojection side optical system is driven by a lens motor 45 for zoomingor focusing.

An image compression/expansion module 31 performs a recording process ofdata compressing a brightness signal and a color difference signal ofthe image signal to be sequentially written on a memory card 32 that isa detachable recording medium through operations using ADCT and theHuffman method.

Further, when in a reproducing mode, the image compression/expansionmodule 31 reads out the image data recorded on the memory card 32 andexpands individual image data that make up a series of dynamic imagesframe by frame. Then, the image compression/expansion module 31 outputsthe image data to the display encoder 24 via the image transformingmodule 23 so as to enable the display of dynamic images and the likebased on the image data stored on the memory card 32.

Operation signals generated at the keys/indicators unit 37 that includesthe main keys and indicators that are provided on the upper panel 11 ofthe casing are sent out directly to the control module 38. Key operationsignals from the remote controller are received by the Ir reception unit35, and code signals are demodulated by an Ir processing module 36 to beoutputted to the control module 38.

An audio processing unit 47 is connected to the control module 38 viathe system bus (SB). This audio processing module 47 includes acircuitry for a sound source such as a PCM sound source. When in aprojection mode and a reproducing mode, the audio processing unit 47converts audio data into analog signals and drives a speaker 48 tooutput loudly sound or voice based on the audio data.

The control module 38 controls a light source control circuit 41 whichis configured as a light source control unit. This light source controlcircuit 41 controls separately and individually an excitation lightsource and a red light source device to emit lights in the red, greenand blue wavelength ranges at predetermined timings so that the lightsin the predetermined wavelength ranges which are required when an imageis generated are emitted from the light source unit 60.

Further, the control module 38 causes a cooling fan drive controlcircuit 43 to detect temperatures through a plurality of temperaturesensors which are provided in the light source unit 60 and the like soas to control the rotating speeds of cooling fans based on the resultsof the temperature detections. The control module 38 also controls thecooling fan drive control circuit 43 so that the cooling fans continueto rotate even after the power supply to the projector 10 itself isturned off through the use of a timer or the power supply to theprojector 10 itself is turned off depending upon the results of thetemperature detections by the temperature sensors.

Next, an internal construction of the projector 10 will be describedbased on what is shown in FIG. 3. FIG. 3 is a schematic plan viewshowing the internal construction of the projector 10. The projector 10includes a control circuit board 241 near the right side panel 14. Thecontrol circuit board 241 includes a power supply circuit block, a lightsource control block and the like. The projector 10 includes the lightsource unit 60 to a side of the control circuit board 241, that is, in asubstantially central portion of the casing of the projector 10.Further, the projector 10 includes a light source side optical system170 and a projection side optical system 220 which are disposed betweenthe light source unit 60 and the left side panel 15.

The light source unit 60 includes a red light source device 120 which isa light source of light in the red wavelength range, an excitation lightshining device 70 which functions not only as a blue light source devicewhich is a light source of light in the blue wavelength range but alsoas an excitation light source, and a green light source 80 which is alight source of light in the green wavelength range. The green lightsource device 80 is made up of the excitation light shining device 70,and a luminescent wheel device 100. Additionally, a light guidingoptical system 140 is disposed in the light source unit 60, and thislight guiding optical system 140 guides and emits lights in the red,green and blue wavelength ranges. The light guiding optical system 140collects lights in the red, green and blue wavelength ranges which areemitted from the red, green and blue light sources, respectively, to anentrance port of a light tunnel 175.

The excitation light shining device 70, which is the excitation lightsource making up the green light source device 80, is disposed at asubstantially central portion in a left-to-right direction of the casingof the projector 10 and near the back panel 13. The excitation lightshining device 70 includes alight source group, a reflecting mirrorgroup 75, a collective lens 78 and a heat sink 81. The light sourcegroup includes blue laser diodes 71 which are a plurality ofsemiconductor devices which are disposed so that their optical axes areparallel to the back panel 13. The reflecting mirror group 75 changesthe direction of axes of lights emitted from the blue laser diodes 71 by90 degrees in the direction of the front panel 12. The collective lens78 collects lights emitted from the blue laser diodes 71 and reflectedby the reflecting mirror group 75. The heat sink 81 is disposed betweenthe blue laser diodes 71 and the right side panel 14.

In the light source group, the blue laser diodes 71 are arranged into amatrix configuration. Collimator lenses 73 are disposed individually onthe optical axes of the blue laser diodes 71, and these collimatorlenses 73 convert lights emitted from the blue laser diodes 71 intoparallel beams so as to enhance the directivity thereof. The reflectingmirror group 75 is configured so that a plurality of reflecting mirrorsare arranged like steps of a staircase and are integrated with a mirrorsubstrate 76 so as to adjust the position thereof, whereby sectionalareas of pencils of light emitted from the blue laser diodes 71 arereduced in one direction for emission to the collective lens 78.

A cooling fan 261 is disposed between the heat sink 81 and the backpanel 13, so that the blue laser diodes 71 are cooled by this coolingfan 261 and the heat sink 81. Further, a cooling fan 261 is alsodisposed between the reflecting mirror group 75 and the back panel 13,so that the reflecting mirror group 75 and the collective lens 78 arecooled by this cooling fan 261.

The red light source device 120 includes a red light source 121 which isdisposed so that an optical axis thereof becomes parallel to the bluelaser diodes 71 and a collective lens group 125 which collects lightemitted from the red light source 121. This red light source 121 is ared light emitting diode which is a semiconductor light emitting elementwhich emits light in the red wavelength range. Then, the red lightsource device 120 is disposed so that the axis of light in the redwavelength range which is emitted from the red light source device 120intersects light in the blue wavelength range which is emitted from theexcitation light shining device 70 and light in the green wavelengthrange which is emitted from a luminescent wheel 101.

Further, the red light source device 120 includes a heat sink 130 whichis disposed on a side of the red light source 121 which faces the rightside panel 14. A cooling fan 261 is disposed between the heat sink 130and the front panel 12, so that the red light source 121 is cooled bythe cooling fan 261 and the heat sink 130.

The luminescent wheel device 100 includes the luminescent wheel 101, awheel motor 110, a collective lens group 107, and a collective lens 115.The luminescent wheel 101 is disposed so as to be parallel to the frontpanel 12, that is, so as to be at right angles to an axis of lightemitted from the excitation light shining device 70. The wheel motor 110drives to rotate the luminescent wheel 101. The collective lens group107 not only collects a pencil of excitation light emitted from theexcitation light shining device 70 to the luminescent wheel 101 but alsocollects a pencil of light which is emitted from the luminescent wheel101 in the direction of the back panel 13. The collective lens 115collects a pencil of light which is emitted from the luminescent wheel101 in the direction of the front panel 12. Additionally, a cooling fan261 is disposed between the wheel motor 110 and the front panel 12, sothat the luminescent wheel device 100 is cooled by this cooling fan 261.

The luminescent wheel 101 includes a luminescent light emitting areawhich emits luminescent light and a diffuse transmission area whereincident light is diffused. A luminescent material layer on theluminescent light emitting area of the luminescent wheel 101 is formedof a green luminescent material. Consequently, when light in the bluewavelength range from the excitation light shining device 70 is shone onto this luminescent material layer as excitation light, the greenluminescent material is excited, whereby light in the green wavelengthrange is emitted in every direction from the green luminescent material.A pencil of light which is produced in a luminescent fashion is emittedto a front side of the luminescent wheel 101 (in other words, a side ofthe luminescent wheel 101 which faces the back panel 13) to be incidenton the collective lens group 107. On the other hand, light in the bluewavelength range which is emitted from the excitation light shiningdevice 70 to be incident on the diffuse transmission area of theluminescent wheel 101 passes through the luminescent wheel 101 whilebeing diffused by the luminescent wheel 101 to be incident on thecollective lens 115 which is disposed on a back side of the luminescentwheel 101 (in other words, aside of the luminescent wheel 101 whichfaces the front panel 12).

The light guiding optical system 140 includes a collective lens whichcollects pencils of light in the red, green and blue wavelength ranges,as well as reflecting mirrors and dichroic mirrors which change thedirections of axes of the red, green and blue lights so that the red,green and blue lights are directed in the same direction. Specifically,in the light guiding optical system 140, a first dichroic mirror 141 isdisposed in a position where the axes of light in the blue wavelengthrange which is emitted from the excitation light shining device 70 andlight in the green wavelength range which is emitted from theluminescent plate 101 intersect the axis of light in the red wavelengthrange which is emitted from the red light source device 120. This firstdichroic mirror 141 transmits excitation light in the blue wavelengthrange and light in the red wavelength range and reflects light in thegreen wavelength range so that the direction of the axis of the light inthe green wavelength range is changed by 90 degrees in the direction ofthe left side panel 15.

A first reflecting mirror 143 is disposed on an axis of light in theblue wavelength range which passes through the luminescent wheel 101while being diffused, that is, between the collective lens 115 and thefront panel 12, and this first reflecting mirror 143 reflects light inthe blue wavelength range so that the direction of the axis of the bluelight is changed by 90 degrees in the direction of the left panel 15. Acollective lens 146 is disposed on a side of the first reflecting mirror143 which faces the left side panel 15, and a second reflecting mirror145 is disposed on a side of the collective lens 146 which faces theleft side panel 115. A collective lens 147 is disposed on a side of thesecond reflecting mirror 145 which faces the back panel 13. The secondreflecting mirror 145 changes the direction of an axis of light in theblue wavelength range, which is reflected by the first reflecting mirror143 to be incident thereon via the collective lens 146, by 90 degrees inthe direction of the back panel 13.

A collective lens 149 is disposed on a side of the first dichroic mirror141 which faces the left side panel 15. Further, a second dichroicmirror 148 is disposed on a side of the collective lens 149 which facesthe left side panel 15 or on a side of the collective lens 147 whichfaces the back panel 13. The second dichroic mirror 148 reflects lightin the red wavelength range and light in the green wavelength range tochange the direction of the axes of the red and green lights by 90degrees in the direction of the back panel 13 and transmits light in theblue wavelength range.

The axis of light in the red wavelength range which passes through thefirst dichroic mirror 141 is caused to coincide with the axis of lightin the green wavelength range which is reflected by the first dichroicmirror 141. Consequently, the light in the red wavelength range whichpasses through the first dichroic mirror 141 and the light in the greenwavelength range which is reflected by the first dichroic mirror 141 areboth incident on the collective lens 149. Then, the light in the redwavelength range and the light in the green wavelength range which passthrough the collective lens 149 are reflected by the second dichroicmirror 148 and are then collected to the entrance port of the lighttunnel 175 via the collective lens 173 of the light source side opticalsystem 170. On the other hand, light in the blue wavelength range whichpasses through the collective lens 147 passes through the seconddichroic mirror 148 and is then collected to the entrance port of thelight tunnel 175 via the collective lens 173.

The light source side optical system 170 includes the collective lens173, the light tunnel 175, a collective lens 178, a light axis changingmirror 181, a collective lens 183, a light shining mirror 185 and acondenser lens 195. The condenser lens 195 emits image light, which isemitted from the display device 51 which is disposed on a side of thecondenser lens 195 which faces the back panel 13, towards the projectionside optical system 220, and therefore, the condenser lens 195 is alsounderstood to be part of the projection side optical system 220.

The collective lens 173 is disposed near the light tunnel 175, and thiscollective lens 173 collects light source light to the entrance port ofthe light tunnel 175. Thus, light in the red wavelength range, light inthe green wavelength range and light in the blue wavelength range arecollected by the collective lens 173 to be incident on the light tunnel175. Pencils of light which are incident on the light tunnel 175 aredistributed uniformly in terms of intensity by the light tunnel 175.

The light axis changing mirror 181 is disposed subsequent to thecollective lens 178 on an optical axis of the light tunnel 175 on a sidethe light tunnel 175 which faces the back panel 13. The pencils of lightwhich exit from an exit port of the light tunnel 175 are collected bythe collective lens 178, whereafter the direction of axes of the pencilsof light is changed in the direction of the left side panel 15 by thelight axis changing mirror 181.

The pencils of light which are reflected by the light axis changingmirror 181 are collected by the collective lens 183 and are then shoneonto the display device 51 at a predetermined angle via the condenserlens 195 by the shining mirror 185. A heat sink 190 is provided on aside of the display device 51 which faces the back panel 13, so that thedisplay device 51 which is a DMD is cooled by this heat sink 190.

The pencils of light, which are light source lights, shone on to thedisplay device 51 by the light source side optical system 170 arereflected on image forming surfaces of the display device 51 and arethen projected on to a screen via the projection side optical system 220as projection light. Here, the projection side optical system 220includes the condenser lens 195, the movable lens group 235, and a fixedlens group 225. The fixed lens group 225 is incorporated in a fixed lensbarrel. The movable lens group 235 is incorporated in a movable lensbarrel so as to be moved by the lens motor for zooming and focusingadjustments.

By configuring the projector 10 in the way described heretofore, whenthe luminescent wheel 101 is rotated and lights are emitted from theexcitation light shining device 70 and the red light source device 120at different timings, lights in the red, green and blue wavelengthranges are sequentially incident on the collective lens 173 and thelight tunnel 175 via the light guiding optical system 140 and are thenincident on the display device 51 via the light source side opticalsystem 170. Then, the DMD, which is the display device 51 of theprojector 10, displays the red, green and blue lights in a time sharingfashion according to data, whereby a color image can be projected on tothe screen.

Next, the configuration of the luminescent wheel 101 according to theembodiment will be described in greater detail. FIG. 4 is a front viewof the luminescent wheel 101. FIG. 5 is an exploded perspective view ofthe luminescent wheel 101. A reflecting plate 310, which is formed intoa disc shape, is provided on the luminescent wheel 101. The reflectingplate 310 is formed by mirror finishing a surface of a metallic basemade up of copper, aluminum or the like through silver deposition or thelike.

A diffuse plate hole portion 312 is provided so as to be opened in thereflecting plate 310, and this diffuse plate hole portion 312 has an arcshape which is concentric with an outer circumference of the reflectingplate 310. A diffuse plate 320 is inserted in the diffuse plate holeportion 312, and this diffuse plate 320 is formed so as to match the arcshape of the diffuse plate hole portion 312. The diffuse plate 320 isformed of a transparent material such as glass, and fine irregularitiesare formed on a surface of the diffuse plate 320 through sandblasting.Thus, a laser beam emitted from the excitation light shining device 70is diffused at a predetermined diffusing angle by being caused to passthrough the diffuse plate 320.

A luminescent material layer 325 is provided on a front surface of thereflecting plate 310 in an end-to-end relationship with the diffuseplate 320 in a circumferential direction, and this luminescent materiallayer 325 has a C-like annular shape which is concentric with thereflecting plate 310. This luminescent material layer 325 is formed bymixing a green luminescent material uniformly into a binder of a highlytransparent silicone resin or the like and forming the resulting mixtureinto a layer. Consequently, when light emitted from the excitation lightshining device 70 is shone on to the luminescent material layer 325 asexcitation light, the luminescent material layer 325 emits luminescentlight in the green wavelength range. Then, pencils of light emitted in aluminescent fashion in every direction from the green luminescentmaterial in the green luminescent material layer 325 are emitteddirectly towards the excitation light shining device 70 or are emittedindirectly towards the excitation light shining device 70 after havingbeen reflected on a reflecting surface of the reflecting plate 310.

Additionally, two end edges 326 of the luminescent material layer 325are situated on the diffuse plate 320. Namely, end portions of theluminescent material layer 325 are provided so as to overlap the diffuseplate 320 in such a way as to be situated thereon. Consequently, jointsbetween circumferential end edges 321 of the diffuse plate 320 and thediffuse plate 312 are covered by the luminescent material layer 325.

An opening portion 316 is formed in the reflecting plate 310 on anopposite side to a side where the diffuse plate hole portion 312 isformed. The opening portion 316 is opened so as to correspond to theposition and size of the diffuse plate hole portion 312 to balance thereflecting plate 310 when the reflecting plate 310 is rotated.

A front side supporting plate (a first supporting plate) 330 is providedon a front side of the reflecting plate 310, and this front sidesupporting plate 330 has a circular disc shape and is formed of a metalsuch as an aluminum material. An outer circumferential edge 331 of thefront side supporting plate 330 extends further radially outwards thanan inner circumferential edge 322 of the diffuse plate 320.Consequently, a front surface of the diffuse plate 320 lying near theinner circumferential edge 322 thereof is supported by the front sidesupporting plate 330 while overlapping the diffuse plate 320 on aradially inner side of the reflecting plate 310.

Aback side supporting plate (a second supporting plate) 340 is providedon a back side of the reflecting plate 310, and this back sidesupporting plate 340 has a circular disc shape and is formed of a metalsuch as a stainless steel material. Two transmitting portions 341, 345are formed in the back side supporting plate 340. The transmittingportions 341, 345 are each opened into an arc shape which is concentricwith the back side supporting plate 340. The one transmitting portion341 is provided so as to correspond to the diffuse plate 320, and theother transmitting portion 345 is formed on an opposite side to a sidewhere the one transmitting portion 341 is formed. In this way, the twotransmitting portions 341 and 345 which have the same shape are providedin the back side supporting plate 340 so as to balance the back sidesupporting plate 340 when it is rotated. Then, light which passesthrough the diffuse plate 320 passes through the transmitting portion341.

A radius of curvature of an inner circumferential edge 342 of thetransmitting portion 341 is the same as a radius of curvature of anouter circumferential edge 331 of the front side supporting plate 330,whereby the inner circumferential edge 342 follows the outercircumferential edge 331. Namely, the inner circumferential edge 342 isprovided so as to extend further radially outwards than the innercircumferential edge 322 of the diffuse plate 320. Consequently, a backsurface of the diffuse plate 320 which lies near the innercircumferential edge 322 thereof is supported by the back side whileoverlapping the diffuse plate 320.

Further, circumferential end edges 343 of the transmitting portion 341are provided so as to lie further circumferentially inwards than thecircumferential end edges 321 of the diffuse plate 320. Consequently,portions of the front surface of the back side supporting plate 340which lie near the end edges 343 are brought into abutment with portionsof the back surface of the diffuse plate 320 which lie near the endedges 321 thereof. Thus, both end portions of the diffuse plate 320 aresupported by the back side supporting plate 340 from a back side of theluminescent wheel 101.

The wheel motor 110 is an outer-rotor-type motor. Mounting hole portions318, 338, 348 of the reflecting plate 310, the front side supportingplate 330 and the back side supporting plate 340 are fitted on a shaftportion 111 of the wheel motor 110. A mounting hole portion 358 of abalance wheel 350 having a circular disc shape is fixed to the shaftportion 111 from the front side of the front side supporting plate 330,whereby the reflecting plate 310, the front side supporting plate 330and the back side supporting plate 340 are connected to the wheel motor110 to thereby be driven to rotate by the wheel motor 110. The rotatingbalance of the luminescent wheel 101 is finally adjusted by applying anadhesive or the like to an inner edge of the balance wheel 350 on afront side thereof.

Next, FIG. 6 shows a sectional view of the luminescent wheel taken alonga line VI-VI in FIG. 4. As has been described before, the portion of thediffuse plate 320 which lies near the inner circumferential edge 322thereof is held by the portion of the front side supporting plate 330which lies near the outer circumferential edge 331 thereof and theportion of the back side supporting plate 340 which lies near the innercircumferential edge 342 of the transmitting portion 341. Additionally,an outer circumferential frame 314 is formed outwards of the diffuseplate hole portion 312 or radially outwards of the diffuse plate 320.The diffuse plate 320 is fastened by this outer circumferential frame314 in relation to a direction in which a centrifugal force is applied.

The circumferential end portions of the diffuse plate 320 can be exposedby means of the construction in which the diffuse plate 320 is fastenedby the outer circumferential frame 314 in relation to the centrifugaldirection thereof. Consequently, compared with the conventionalluminescent wheel 501 shown in FIG. 9, since the area where the diffuseplate 320 is not used can be reduced, the utilization efficiency of thediffuse plate 320 can be increased. Similarly, an outer circumferentialframe 344 is also formed outwards of the transmitting portion 314 of theback side supporting plate 340. Then, the outer circumferential frame344 and the outer circumferential frame 314 are formed so as to have thesame radial length.

Next, FIG. 7 shows a sectional view of the luminescent wheel taken alonga line VII-VII in FIG. 4. As has been described before, the portions ofthe back surface of the diffuse plate 320 which lie near the end edges321 thereof are supported by the portions of the front surface of theback side supporting plate 340 which lie near the end edges 343 of thetransmitting portion 341. Further, the luminescent material layer 325 isprovided so that portions thereof which lie near the end edges 326thereof overlap the diffuse plate 320.

Next, FIG. 8 shows a sectional view of the luminescent wheel taken alonga line VIII-VIII in FIG. 4. As has been described before, theluminescent material layer 325 is provided on the reflecting plate 310.Consequently, in luminescent light that is emitted as a result of theluminescent material in the luminescent material layer 325 being excitedby excitation light, luminescent light which is emitted to a back sideof the luminescent wheel 101 is reflected by the reflecting plate 310 tobe emitted to a front side of the luminescent wheel 101.

Thus, while the embodiment of the invention has been describedheretofore, the invention is not limited by the embodiment and hence canbe carried out in various modes. For example, in the embodiment, whilethe front side supporting plate 330 is formed of the aluminum material,the front side supporting plate 330 can also be formed of othermaterials. Similarly, while the back side supporting plate 340 is formedof the stainless steel material, the backside supporting plate 340 canalso be formed of other materials.

Additionally, in the embodiment, while the diffuse plate 320 is providedin the diffuse plate hole portion 312, as with the conventionalluminescent wheel 501 shown in FIG. 9, a configuration may be adopted inwhich a cut-out portion is formed and the diffuse plate 320 is fastenedby claw portions 533 in relation to a centrifugal direction. Similarly,the transmitting portion 341 of the back side supporting plate 340 maybe formed as a cut-out portion.

As has been described above, the reflecting plate 310 of the luminescentwheel 101 according to the embodiment of the invention includes thediffuse plate 320 and the luminescent material layer 325 which areprovided in the end-to-end relationship with each other in thecircumferential direction. The front side supporting plate 330, which isthe first supporting plate, is provided on the front side of thereflecting plate 310 which constitutes the one side thereof in such away as to support part of the diffuse plate 320. The back sidesupporting plate 340, which is the second supporting plate, is providedon the back side of the reflecting plate 310 which constitutes the otherside thereof in such a way as to support another part of the diffuseplate 320.

By adopting this configuration, the front side supporting plate 330 andthe luminescent material layer 325 can be provided on the front surfaceof the reflecting plate 310. Consequently, since the luminescent wheel101 can be configured as the three-layer construction made up of thefront side supporting plate 330 and the luminescent material layer 325,the back side supporting plate 340, and the reflecting plate 310, thethickness of the luminescent wheel 101 can be reduced. Further, sincethe front side supporting plate 330 and the back side supporting plate340 should have rigidity which is sufficient to hold the diffuse plate320 therebetween, both the supporting plates can be formed of a thinplate material, whereby the luminescent wheel 101 can be formed thinner.

Further, the diffuse plate 320 is provided in the diffuse plate holeportion 312 in the reflecting plate 310 on which the luminescentmaterial layer 325 is provided. Consequently, since the surface of theluminescent material layer 325 can be made almost same level with thesurface of the diffuse plate 320, the magnitude or intensity ofexcitation light which is shone on to the luminescent layer 325 is equalto the magnitude or intensity of a pencil of light which is transmittedthrough the diffuse plate 320 while being diffused, and therefore, it ispossible to provide the luminescent wheel 101 which can emit light whichis easy to be used when it is used as projection light.

Additionally, the reflecting plate 310 has the circular disc shape. Thefront side supporting plate 330, which is the first supporting plate,overlaps part of the diffuse light 320 which lies on the innercircumferential edge 322 side thereof to thereby support the diffuseplate 320. This can make the supporting structure from the front side ofthe diffuse plate 320 simple, thereby making it possible to reduce thediameter of the front side supporting plate 330.

Additionally, the back side supporting plate 340, which is the secondsupporting plate, overlaps part of the diffuse plate 320 which lies onthe inner circumferential edge 322 side thereof to thereby support thediffuse plate 322. This can make the supporting structure from the backside of the diffuse plate 320 simple.

The luminescent material layer 325 has the C-like annular shape, and theend edges 326 of the C-like annular shape are provided on the uppersurface of the diffuse plate 320 which constitutes one surface thereof.By adopting this configuration, the gaps between the end edges 321 ofthe diffuse plate 320 and the circumferential edges of the diffuse platehole portion 312 are covered by the luminescent material layer 325.Consequently, the luminescent material layer 325 and the diffuse plate320 can be formed continuously in the circumferential direction.

Additionally, the front side supporting plate 330, which is the firstsupporting plate, has the circular disc shape. Since this enables thefront side supporting plate 330 to be formed into the circular diskshape which provides the good rotating balance, it is possible to driveto rotate the luminescent wheel 101 in a well-balanced fashion.

The back side supporting plate 340, which is the second supportingplate, has the transmitting portion 341. The circumferential endportions of the diffuse plate 320 are supported by the portions of thefront surface of the back side supporting plate 340 which lie near thecircumferential end edges 343 of the transmitting portion 341 from theback side which is the other side. In fabricating the luminescent wheel101, the diffuse plate 320 is temporarily placed on the back sidesupporting plate 340 to perform other fabricating steps, whereby thenumber of man-hours involved in the fabrication of the luminescent wheel101 can be reduced.

The front side supporting plate 330, which is the first supportingplate, is formed of the metal containing aluminum such as the aluminummaterial, and the back side supporting plate 340, which is the secondsupporting plate, is formed of the metal containing stainless steel suchas the stainless steel material. This enables the front side supportingplate 330 to be formed as the light member and the back side supportingmember 340 to be formed as the highly rigid member.

The light source unit 60 has the luminescent wheel device 100, theexcitation light shining device 70 which emits light in the bluewavelength range, and the red light source device 120 which emits lightin the red wavelength range. The luminescent material layer 325 of theluminescent wheel 101 emits light in the green wavelength range as aresult of excitation light emitted from the excitation light shiningdevice 70 being shone on thereto. This enables the reduction in size ofthe luminescent wheel device 100 through the use of the luminescentwheel 101 which is formed thin, and therefore, it is possible to providethe small light source unit 60 which can emit light source lights of thethree primary colors.

The projector 10 has the light source unit 60, the display device 51,the projection side optical system 220 and the projector control unit.This makes it possible to obtain the projector 10 which is made smallerin size.

The embodiment that has been described heretofore is provided as theexample, and hence, there is no intention of limiting the scope of theinvention by the embodiment. The novel embodiment can be carried out inother various forms, and various omissions, replacements and/ormodifications can be made thereto without departing from the spirit andscope of the invention. The resulting embodiments or their modificationsare contained in the spirit and scope of the invention and are alsocontained in the scope of inventions which will be claimed hereafter andtheir equivalents.

What is claimed is:
 1. A luminescent wheel comprising: a reflectingplate on which a diffuse plate and a luminescent material layer areprovided in an end-to-end relationship with each other in acircumferential direction, wherein the reflecting plate has a circulardisc shape; a first supporting plate which is provided on one surface ofthe reflecting plate to support part of the diffuse plate; and a secondsupporting plate which is provided on the other surface of thereflecting plate to support the part of the diffuse plate; wherein thefirst supporting plate overlaps an inner circumferential edge sideportion of the diffuse plate to support the diffuse plate, and whereinthe second supporting plate overlaps the inner circumferential edge sideportion of the diffuse plate to support the diffuse plate.
 2. Theluminescent wheel according to claim 1, wherein the first supportingplate, the diffuse plate, and the second supporting plate all overlapeach other only at the inner circumferential edge side portion of thediffuse plate.
 3. The luminescent wheel according to claim 1, whereinthe luminescent material layer has a C-like annular shape, and an endportion of the C-like annular shape is provided on one surface of thediffuse plate.
 4. The luminescent wheel according to claim 2, whereinthe luminescent material layer has a C-like annular shape, and an endportion of the C-like annular shape is provided on one surface of thediffuse plate.
 5. The luminescent wheel according to claim 1, whereinthe first supporting plate has a circular disc shape.
 6. The luminescentwheel according to claim 1, wherein the second supporting plate has atransmitting portion which transmits light which is transmitted throughthe diffuse plate, and wherein end portions of the diffuse plate aresupported by portions of the second supporting plate lying near bothcircumferential end portions of the transmitting portion.
 7. Theluminescent wheel according to claim 1, wherein the first supportingplate is formed of a metal containing aluminum, and the secondsupporting plate is formed of a metal containing stainless steel.
 8. Alight source unit comprising: a luminescent wheel device comprising theluminescent wheel according to claim 1; an excitation light shiningdevice which comprises a semiconductor light emitting element to emitlight in the blue wavelength range as excitation light; and a red lightsource device which comprises a semiconductor light emitting device toemit light in the red wavelength range, wherein the luminescent materiallayer emits light in the green wavelength range as a result of theexcitation light being shone thereon.
 9. A projector comprising: thelight source unit according to claim 8; a display device onto whichlight source light from the light source unit is shone to form imagelight; a projection side optical system which projects the image lightemitted from the display device onto a screen; and a projector controlunit configured to control the display device and the light source unit.10. A luminescent wheel comprising: a reflecting plate on which adiffuse plate and a luminescent material layer are provided in acircumferential direction, wherein the reflecting plate has a circulardisc shape; a first supporting plate; and a second supporting plate,wherein an inner circumferential side portion of the diffuse plate isheld by the second supporting plate and an outer circumferential edge ofthe first supporting plate.
 11. The luminescent wheel according to claim10, wherein the second supporting plate has a transmitting portion whichtransmits light which is transmitted through the diffuse plate, andwherein the inner circumferential side portion of the diffuse plate isheld by an inner circumferential edge of the transmitting portion andthe outer circumferential edge of the first supporting plate.
 12. Theluminescent wheel according to claim 10, wherein the luminescentmaterial layer has a C-like annular shape, and an end portion of theC-like annular shape is provided on one surface of the diffuse plate.13. The luminescent wheel according to claim 11, wherein the luminescentmaterial layer has a C-like annular shape, and an end portion of theC-like annular shape is provided on one surface of the diffuse plate.14. The luminescent wheel according to claim 10, wherein the firstsupporting plate has a circular disc shape.
 15. The luminescent wheelaccording to claim 10, wherein the second supporting plate has atransmitting portion which transmits light which is transmitted throughthe diffuse plate, and wherein end portions of the diffuse plate aresupported by portions of the second supporting plate lying near bothcircumferential end portions of the transmitting portion.
 16. Theluminescent wheel according to claim 10, wherein the first supportingplate is formed of a metal containing aluminum, and the secondsupporting plate is formed of a metal containing stainless steel.
 17. Alight source unit comprising: a luminescent wheel device comprising theluminescent wheel according to claim 10; an excitation light shiningdevice which comprises a semiconductor light emitting element to emitlight in the blue wavelength range as excitation light; and a red lightsource device which comprises a semiconductor light emitting device toemit light in the red wavelength range, wherein the luminescent materiallayer emits light in the green wavelength range as a result of theexcitation light being shone thereon.
 18. A projector comprising: thelight source unit according to claim 17; a display device onto whichlight source light from the light source unit is shone to form imagelight; a projection side optical system which projects the image lightemitted from the display device onto a screen; and a projector controlunit configured to control the display device and the light source unit.